This question is incomplete. The options are:
a. Oligocene b. Eocenec. Miocened. Pleistocene
Option b is correct. This relates to the Paleocene-Eocene Thermal Maximum (PETM) which occured around 56 million years ago and was similar to modern-day climate change. Warming of more than 5 degrees Celcius occured over 15-20 thousand years because of input of more than 2000 gigatons of carbon into the atmosphere. The PETM resulted in mass deep ocean extinctions and mass terrestrial and shallow ocean diversification.
